Place the item you want to measure between the anvil -- the stationary measuring face attached to the micrometer's frame -- and the spindle -- the
Rotate the thimble -- the handle of the micrometer -- until the object is tight between the anvil and the spindle.
Count the number of major numbered divisions revealed on the sleeve. Each one of these represents a tenth of an inch (0.1").
Count the number of minor unnumbered divisions revealed after the closest whole number. Each one is twenty-five thousandths of an inch (0.025").
Read the line on the thimble that lines up with the data line on the sleeve. This gives thousandths of an inch (0.001").
Add everything together. For example, if the sleeve reveals the data line up to three minor divisions past the "2" mark, and lines up with the "13" mark on the thimble, you have two-tenths (0.2") plus seventy-five thousandths (0.075") plus eleven thousandths (0.011"), for a measurement of 0.286 inches.